A charged particle beam device for acquiring specimen information on an irradiation position by irradiating charged particle on a specimen as a probe and detecting charged particles released from the irradiation position is widely known. For example, in a scanning electron microscope (SEM), an electron beam probe converged over a specimen is 2-dimensionally scanned and secondary electrons (SE) with a relatively low energy from 0 to 50 eV and backscattered electrons (BSE) having a wide distribution from 50 eV to the arrival energy of a primary electron beam are detected and imaged. It is generally known that different information is acquired for SE and BSE based on ranges of energy to be detected (energy discrimination).
For example, SE of several eV reflects information on a specimen surface and unevenness, and SE of higher energy reflects information on the interior of a specimen. Also, potential information on the specimen surface may be reflected. BSE reflects specimen composition information and crystallinity information and information on a deeper level of the interior of a specimen than SE.
In recent SEMs, angle discrimination is highlighted in addition to the energy discrimination of SE and BSE. In particular, since BSE has higher energy than SE, and it is less susceptible to an electric field from a specimen or a magnetic field of a primary beam, thus BSE reaches a detector while maintaining an angular distribution at the time of emission from the specimen. PTL 1 discloses an SEM that selectively detects electrons emitted in a specific direction by dividing a detector element axially symmetrically around the light axis of an electron beam or at different relative angles with respect to the light axis. Further, PTL 2 discloses a SEM including a detector with two stages in the light axis direction or detectors divided axially symmetrically about the light axis or at different relative angles with respect to the light axis. Furthermore, PTL 3 discloses a scanning electron microscope including a backscattered electron detector movable in the horizontal direction or the vertical direction.